A semiconductor or integrated circuit (IC) device may comprise many miniaturized circuits implemented on a semiconductor substrate. IC devices are commonly tested in order to ensure proper operation before being used. IC devices can be tested in a limited fashion using built-in self test (BIST) circuitry. However, BIST testing is incomplete and does not test all aspects of operation. Thorough testing of an IC device is therefore accomplished using complex external testing equipment. In order for complex test equipment to be used, many dedicated external input/output (I/O) terminals are typically required to allow the test equipment to input various test patterns, codes, and data, and to stress the circuitry of the IC device. However, in an environment where multiple IC devices are combined within a single semiconductor device package having a limited number of input/output terminals it can be difficult, if not impossible, to use external testing equipment for testing one or more of the multiple IC devices thoroughly. Often, the addition of dedicated external terminals is impractical.